Novel polymers and their use in photographic applications



United States Patent M US. Cl. 26079.3 Claims ABSTRACT OF THE DISCLOSURE Polymers which are substantially water insoluble comprising (1) units of acrylic acid, (2) units of monomer represented by the formula:

where R is a hydrogen atom or methyl group and R is an alkyl radical with (3) units of monomer having the formula:

where R is a hydrogen atom or alkyl group, R and R are each divalent saturated aliphatic hydrocarbon radicals and R and R each represent hydrogen atoms or alkyl groups; wherein said interpolymer comprises up to by weight, of said (1), at least about 75%, by weight, of said (2) and up to about 10%, by weight, of said (3).

This application is a divisional application of Ser. No. 449,879, filed Apr. 21, 1965, now US. Pat. 3,411,912.

This invention relates to novel interpolymers of acrylic acid, unsaturated carboxylic acid esters and sulfobetaines. More particularly, this invention relates to the use of such interpolymers in photographic silver halide compositions. In a specific aspect, this invention relates to photographic elements which contain said novel interpolymers in at least one layer.

Gelatin is generally used in the preparation of photographic silver halide emulsions because of its good dispersing properties and its excellent protective colloid properties. However, gelatin is susceptible to dimensional change when subjected to varying temperature or humidity and like conditions. Various natural and synthetic materials have been proposed as substitutes for gelatin in one or more layers of a photographic element to provide dimensional stability. However, many of these materials will salt-out, i.e., coagulate, in the presence of organic or inorganic salts which are often present in photographic silver halide compositions. It is evident, therefore, that a substitute for gelatin which combines improved dimensional stability with good salt tolerance will greatly enhance the art.

Accordingly, it is an object of this invention to provide a polymer of acrylic acid, an unsaturated carboxylic acid ester and a sulfobetaine which polymer exhibits a desirable combination of physical properties.

Another object of this invention is to provide novel and improved photographic compositions.

A further object of this invention is to provide novel interpolymers which can be used in photographic applications and which resist coagulation or salting out in the presence of inorganic or organic salts.

3,549,605 Patented Dec. 22, 1970 Another object of this invention is to provide novel polymer dispersions which are particularly useful in photographic applications.

A further object of this invention is to provide photographic elements comprising a photographic silver halide layer and, incorporated in at least one layer of said photographic element, interpolymers of acrylic acid, unsaturated carboxylic acid esters and sulfobetaines.

A sill further object of this invention is to provide photographic silver halide emulsions in which at least a part of the binding agent for the silver halide comprises a novel interpolymer as described herein.

Other objects of the invention will become apparent from an examination of the specification and claims that follow.

In accordance with the invention, the above objects are attained with film forming interpolymers of (1) up to about 15 by weight, of acrylic acid, (2) at least about by weight, of a monomer having the formula:

where R is hydrogen or methyl and R is an alkyl radical, desirably containing 1-12 carbon atoms, with (3) up to about 10%, by weight, of a monomer having the formula:

where R is hydrogen or alkyl, R and R are each divalent saturated aliphatic hydrocarbon radicals, desirably containing up to 12 carbon atoms and R and R are each hydrogen or alkyl.

The novel interpolymers of this invention are excellent substitutes for gelatin in photographic applications since they exhibit not only excellent salt tolerance in the form of latices or dispersions, but they also exhibit excellent dimensional stability, photographic inertness, water insolubility and water permeability. In addition, these copolymers exhibit good compatibility with gelatin which makes it possible to replace only a small part of the gelatin in a photographic composition, depending upon the particular combination of properties desired.

A significant feature of this invention is that the properties which make the novel polymers of this invention suitable gelatin substitutes are very closely related to the concentration and nature of the monomers from which the novel polymers are prepared. For example, a significant increase in acrylic acid content over that described herein gives a polymer which is soluble in water. This is undesirable in a gelatin substitute, particularly where it is to be used in unhardened photographic silver halide emulsions. Furthermore, a substantial increase in the sulfobetaine content of the interpolymer results in a product which shows little or no compatibility with gelatin. In addition, the substitution of the alkyl acrylate or methacrylate with such closely related monomers as acrylonitrile results in hard, brittle, film-forming materials which are unsuitable as gelatin substitutes in photographic silver halide emulsions.

As already indicated, the polymers described herein are prepared by interpolymerizing acrylic acid, an unsaturated carboxylic acid ester and a sulfobetaine. The sulfobetaines employed in the preparation of these interpolymers include any of the sulfobetaines having the formula:

where R, R R R and R are each as defined hereinbefore. The R, R and R radicals include any of the alkyl radicals and preferably contain up to about 12 carbon atoms, often 1-8 carbon atoms, as exemplified by methyl, ethyl, propyl, pentyl, octyl, dodecyl and the like. The R and R divalent saturated aliphatic hydrocarbon radicals can be branched or straight chain and will often contain up to 12 carbon atoms, as exemplified by methylene, ethylene, propylene, 1,2-propylene, tetramethylene, 1,3-isobutylene, pentamethylene, hexamethylene, octamethylene and the like. The sulfobetaine-s includes for example, 5,5,10-trimethyl 9 oxo 8 oxa azoniaundecene 1 sulfonate, 4-t-butyl-9-methyl-8-oxo-7- oxa 4 aza 9 decene 1 sulfonic acid, 4,4,9-trimethyl- 8-oxo-7-oxa-4-azonia-9-decene-1 sulfonate and the like.

The sulfobetaines can be prepared using any method known to be suitable for this purpose. A convenient method for preparing the sulfobetaine monomers comprises reacting the appropriate amino alkyl ester of an unsaturated carboxylic acid with the appropriate sultone. Such a reaction can be carried out in the presence of an organic solvent such as acetonitrile, a liquid hydrocarbon or a ketone such as acetone at temperature up to about 100 C., preferably 50 to about 80 C. In general, the reaction is complete in less than 8 hours, often in about 2 to about 6 hours. The reaction is not pressure dependent and therefore superatmospheric or subatmosphereic pressures can be employed. The resulting sulfobetaine can be isolated by conventional procedures. The reactants are generally employed in stoichiometric concentrations although slight excesses of either reactant can be employed. As is obbious to one skilled in the art the specific reaction conditions, for example, temperature, pressure, and the like, will depend upon the particular amino alkyl ester and sultone employed. Another suitable method for preparing the sulfobetaines, particularly where R and R in the above formula are both hydrogen, is to react the appropriate hydroxyalkyl amine with the required sultone and then esterify with acrylic acid or a derivative thereof.

The interpolymers of this invention are prepared by copolymerizing at least one sulfobetaine monomer, as described above, with acrylic acid and at least one ethylenically unsaturated acrylic ester having the formula:

where R is hydrogen or methyl and R is an alkyl radical. Suitable alkyl radicals include, for example, ethyl, methyl, propyl, pentyl, dodecyl and the like. Suitable monomers include for example, ethyl acrylate, methyl acrylate, butyl acrylate, ethyl methacrylate, octyl methacrylate, and the like. The interpolymers employed in practicing this invention contain, in polymerized form, up to about preferably about 5 to about 15%, by weight, of polymerized acrylic acid, at least about 75%, preferably about 75 to about 93%, by weight, of acrylate and/or methacrylate and up to about 10%, preferably about 2 to about 10%, by weight, of the sulfobetaine reactant. Such polymers are film forming and generally have an average molecular weight in the range of about 5000 to about 500,000 or more.

The temperature at which the interpolymers of this invention are prepared is subject to wide variation since this temperature depends upon such variable features as the specific monomers used, the duration of heating, pressure employed, and like considerations. However, the polymerization temperature generally does not exceed about 100 C., and most often, is in the range of about 50 to about 90 C. The polymerization can be carried out in suitable solvents or diluents, for example, water or mixtures of water with water miscible solvents, as exemplified by methanol, ethanol, propanol, isopropyl alcohol, butyl alcohol, and the like. The pressure employed in the polymerization, if any, is usually only sufficient to maintain the reaction mixture in liquid form, although either superatmospheric or subatmospheric pressures can be used. The concentation of polymerizable monomer in the polymerization mixture can be varied Widely with concentrations up to about 40 percent, by Weight, and preferably about 20 to about 40 percent, by Weight, based on the weight of vehicle being satisfactory. Suitable catalysts for the polymerization reaction include, for example, the free radical catalysts, such as hydrogen peroxide, cumene hydroperoxide, water soluble azo type initiators and the like. In redox polymerization systems the usual ingredients can be employed. If desired, the polymer can be isolated from the reaction vehicle by freezing, salting out, coagulation or by using other separation procedures suitable for this purpose.

Dispersions of the photographic silver halide in the novel interpolymers of this invention, in combination with other binding agents, such as gelatin, can be made in a variety of ways. For example, an aqueous gelatin dispersion of the photographic silver halide can be mixed with an aqueous dispersion of the interpolymer. Alternatively, the photographic silver halide can be precipitated in an aqueous dispersion of the interpolymer of other colloid. In this case, a water soluble silver salt such as silver nitrate is admixed with a water soluble halide such as potassium bromide in the presence of the mixture. In still another procedure, the photographic silver halide is precipiated in an aqueous gelatin solution and digested in the conventional manner known to the art. After digestion, but prior to coating, there is added to the emulsion an aqueous dispersion of the interpolymer of this invention. The bulk of the resulting dispersions can be increased by the addition of more of the interpolymer and/or natural or synthetic colloids or binding agents suitable for use in photographic silver halide emulsions. Satisfactory colloids include, for example, gelatin, colloidal albumin, cellulose derivatives, synthetic resins such as polyvinyl compounds and the like.

The interpolymers of this invention can be employed in one or more layers of a photographic silver halide element. However, the interpolymers described herein do not exhibit the very good peptizing action for silver halides shown by such binding agents as gelatin or other colloids. Therefore, photographic silver halide emulsions in which the interpolymers of this invention are used contain at least some binding agent such as gelatin which exhibits the required peptizing action. Generally, binding agents which comprise about 10 to about often at least 50%, and most often about 40 to about 65%, by weight, of the novel polymers described herein, give good results in photographic silver halide emulsions. In the preferred case, the remainder of the binding agent is gelatin, although other colloids also give good results. As already indicated, where the polymers are used in photographic elements in layers other than the emulsion layers, for example, in filter layers, antihalation layers, antiabrasion layers, antistatic layers and barrier layers, they can be used as the sole vehicle or in admixture with the natural or synthetic colloids mentioned above. The silver halide employed in the preparation of light sensitive coatings described herein includes any of the photographic silver halides as exemplified by silver bromide, silver chloride and silver iodide, or mixed silver halides such as silver chlorobromide, silver bromoiodide, and the like.

The photographic compositions described herein can be coated on a wide variety of supports. Typical supports are cellulose nitrate film, cellulose acetate film, polyvinyl acetal film, polystyrene film, polyethylene terephthalate film and related films or resinous materials as well as glass, paper, wood and the like. Supports such as paper are coated with a-olefin polymers, particularly polymers of a-olefins containing 210 carbon atoms as exemplified by polyethylene, polypropylene and ethylene-butene copolymers and the like can also be employed.

The emulsions containing the novel interpolymers of this invention can be chemically sensitized with compounds of the sulfur group, noble metal salts such as gold salts, reduction sensitized with reducing agents, and combinations of these. Furthermore, emulsion layers and other layers present in photographic elements made according to this invention can be hardened with any suitable hardener such as aldehyde hardeners, aziridine hardeners, hardeners which are derivatives of dioxane, oxypolysaccharides such as oxystarch, oxy plant gums, and the like.

The emulsion can also contain additional additives, particularly those known to be beneficial in photographic emulsions, including for example, stabilizers or antifoggants, particularly the water soluble inorganic acid salts of cadmium cobalt manganese and zinc as disclosed in U.S. Pat. 2,829,404, the substituted trianzaindolizines as disclosed in U.S. Pats. 2,444,605 and 2,444,607, speed increasing materials, plasticizers and the like. Sensitizers which give particularly good results in the photographic compositions disclosed herein are the alkylene oxide polymers which can be employed alone or in combination with other materials, such as quaternary ammonium salts, as disclosed in U.S. Pat. 2,886,437 or with mercury compounds and nitrogen containing compounds, as disclosed in U.S. Pat. 2,751,299.

The polymers of this invention can be used in various kinds of photographic emulsions. For example, they can be used in X-ray and other non-spectrally sensitized emulsions as well as orthochromatic, panchromatic and infrared sensitive emulsions, particularly those sensitized with merocyanine dyes, cyanine dyes, carbocyanine dyes and the like. Furthermore, the polymers of this invention can be used in emulsions intended for color photography, for example, emulsions containing color forming couplers or emulsions to be developed by solutions containing couplers or other color generating materials. In addition, these polymers can be used in emulsions intended for use in diffusion transfer processes which utilize the nondeveloped silver halide in the non-image areas of the negative to form a positive by dissolving the undeveloped silver halide and precipitating it on a receiver layer in close proximity to the original silver halide emulsion layer. Such processes are described in Rott U.S. Pat. 2,352,014, Land U.S. Pat. 2,543,181 and Yackel et al. U.S. Pat. 3,020,155. The novel polymers described herein can also be used in color transfer processes which utilize the diffusion transfer of an imagewise distribution of developer, coupler or dye from a light sensitive layer to a second layer while the two layers are in close proximity to one another. Color transfer processes of this type are described in Yutzy U.S. Pat. 2,856,142, Land et al. U.S. Pat. 2,983,606, Whitmore et al. British Pats. 904,364 and 840,731 and Whitmore et al. U.S. application Ser. No. 392,471. Silver halide emulsions containing these polymers can be processed in monobath processes such as described in Haist et al. U.S. Pat. 2,875,048 or in stabilization type processes.

This invention can be further illustrated by the following examples of preferred embodiments thereof although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.

EXAMPLE 1 As already indicated, the sulfobetaine monomers described herein can be prepared by reacting an amino alkyl ester with a sultone. To illustrate, a solution of 12.2 g. (0.1 mole) of 1,3-propane sultone and 15.7 g. (0.1 mole) of dimethylaminoethyl methacrylate and 100 milliliters of acetonitrile is refluxed for two hours. The precipitated product is separated from the liquid, washed with hot acetonitrile and dried in vacuum. 27.4 g. of white crystal- 6 line 4,4,9 trimethyl 8 oxo-7-oxa-4-azonia-9-decene-lsulfonate is obtained.

The sulfobetaine monomer can be interpolymerized with acrylic acid and unsaturated carboxylic acid esters to form novel interpolymers having good salt tolerance.

To illustrate, 375 ml. of distilled water is placed in a flask, heated to C. and degassed with nitrogen. 3.9 ml. of Triton 770 1 (40% solution), 1.5 g. of potassium persulfate and 0.5 g. of sodium bisulfate are then added in the order given. After the additions, the following two solutions are added under nitrogen with vigorous stirring over a period of 12 minutes: (1) a solution of 107 g. of ethyl acrylate and 5.5 g. of acrylic acid and (2) 3.9 ml. of Triton 770 (40% solution) and 12.5 g. of 4,4,9-tri methyl-8-oxo-7-oxa-4-azonia-9-decene-1 sulfonate, prepared as above, in 125 ml. of water. After the reaction mixture is stirred for an additional 30 minutes at 80 C. it is diluted to 10% solids with water.

The latex obtained is highly resistant to coagulation in sodium chloride, calcium chloride and triethyl amine hydrochloride salts. To illustrate, the addition of polymer latex does not precipitate upon the addition of various salt solutions, including 10% aqueous solutions of zinc acetate, cadmium chloride, barium chloride, magnesium sulfate, calcium chloride, sodium chloride and the like.

In contrast, a polymer which is prepared in the absence of the sulfobetaine monomers immediately precipitates upon exposure to these solutions. Thus, the aforementioned salt solutions all immediately precipitate an equeous dispersion of a copolymer of ethyl acrylate with acrylic acid (:5 by weight). Furthermore, when the ethyl acrylate monomer is replaced with acrylonitrile the interpolymer forms a hard, brittle film which is not a suitable binding agent for photographic emulsions.

EXAMPLE 2 Example 1 is repeated except that solution (1) comprises 15.4 g. of acrylic acid and 138.6 g. of n-butyl acrylate. Upon testing in the manner described in Example 1, the emulsion obtained is shown to be significantly tolerant to the presence of sodium chloride salts.

EXAMPLE 3 The polymerization procedure described in Example 1 is repeated using a catalyst system of 1.0 g. of potassium persulfate and 1.2 g. of sodium dithionite. The sodium dithionite is supplied by the latter of the following two solutions which are added simultaneously over a period of 11 minutes: (1) 15.8 g. of acrylic acid and 142 g. of n-butyl acrylate, (2) '1.27 g. of sodium dithionite, 3.9 ml. of Triton 77 (40% solution) and 8.3 g. of 4,4,9-trimethyl-8-oxo-7-oxa-4-azonia-9-decene-l-sulfonate in ml. of water. Excess potassium persulfate is removed from the emulsion by titration with 10% sodium dithionite. The slight excess of sodium dithionite is removed by heating. The catalyst free emulsion resists coagulation when exposed to sodium chloride and organic salts such as triethylamine hydrochloride.

EXAMPLE 4 A solution of 78.5 g. (0.5 mole) of N,N-dimethylaminoethyl methacrylate and 68.0 g. (0.5 mole) of 1,4-butane sultone and 250 ml. of acetonitrile is refluxed for 1% hours during which time the sulfobetaine precipitates. To the reaction mixture is added 200 ml. of diethyl ether. The product is isolated by filtration, washed and dried in vacuo. There is obtained 78.5 g. of 5,5,l0-trimethyl-9-ox0- 8-oxa-5-azonia-IO-undecene-l-sulfonate (54% of theoretical yield).

Using the procedure of Example 1, 11.6 g. of acrylic acid, 10.4 g. of n-butyl acrylate and 9.4 g. of 5,5,10-trimethyl-9-oxo-8-oxa-5-azonia-10-undecene-1-sulfonate are sogiflll'lillltonlkqw is1 a 1surtflzltctanclfctgmposciltion composed of a ayary poye ersuaean lsoroa factured by Rohm and Haas Co. p p no], mm

polymerized at 95 C. The latex, at pH 5.0, is stable to the addition of concentrated divalent cationic salt solutions when tested as in Example 1.

EXAMPLE A solution of 55.6 g. (0.3 mole) of t-butylaminoethyl methacrylate and 36.6 g. (0.3 mole) of 1,3-pro ane sultone in 150 ml. of acetonitrile is refluxed for 8 hours.

The solution is evaporated to a viscous oil which crystal-.

lizes upon addition of acetone. The product is separated by filtration and dried in vacuo. Recrystallization from ethanol gives 28.6 g. of crystalline, solid 4-t-butyl-9- methyl-8-oxo-7-oxa-9-decene-l-sulfonic acid.

The procedure of Example 1 is repeated with 16.0 g. of acrylic acid, 142.2 g. of n-butyl acrylate and 8.3 g. of the sulfobetaine monomer prepared using the above procedure. The polymerization is carried out at 95 C. to form an emulsion interpolymer which, at pH 5, is stable to the addition of concentrated solutions of divalent cationic salts.

EXAMPLE 6 The interpolymers prepared as described herein can be employed in photographic silver halide emulsions. To illustrate, the polymer latex described in Example 3 is combined with a gelatino-silver halide photographic emulsion having a high salt content. The emulsion is coated on a conventional film support and gives a smooth homogeneous coating. In addition, reducing the gelatin content of the emulsion and replacing part of the gelatin with the polymeric latex of Example 3 improves the dimensional stability of the product.

EXAMPLE 7 The novel polymers of this invention can be used in photographic silver halide emulsions without any substantial detrimental effect in photographic properties even though there is a very desirable improvement in dimensional stability and salt tolerance. To illustrate, a high contrast litho type silver chlorobrornoiodide gelatin emulsion containing 55 millimoles (10.1 g.) of cadmium chloride per mole of silver is coated on polyethylene terephthalate film support with the following changes in binding agent: Coating A contains 107 g. of gelatin per mole of silver and is coated at 456 mg. of silver and 451 mg. of gelatin per square foot; Coating B contains 40 g. of gelatin and 80 g. of the polymer (dry weight) contained in Example 2, per mole of silver and is coated at a coverage of 456 mg. of silver and 511 mg. of vehicle per square foot. In a third composition, 80 g. per mole of silver of butyl acrylate-acrylic acid copolymer, 90:10 by weight, is added to an emulsion containing 40 g. of gelatin per mole of silver. In this last case the cadmium salt in the emulsion causes immediate coagulation of the butyl acrylate-acrylic acid copolymer so that the emulsion cannot be coated on the support.

Samples of the films from Coatings A and B are exposed in an Eastman IB Sensitometer, developed for 3% minutes in a hydroquinone-low sulfite-ion developer such as Kodak D85, fixed, washed and dried. The photographic characteristics of the coatings are as follows:

Relative speed Gamma Fog Coating:

EXAMPLE 8 As previously pointed out the novel interpolymers of this invention can be used in photographic elements in layers other than, or in addition to, the photographic silver halide layer. For example, these interpolymers can be used in stripping layers to improve stripping. To illustrate, the layers of a matrix stripping film are coated on a polyester support in the following order; (1) an unhardened gelatin layer (coverage 50 mg./ft. containing a conventional antihalation dye and a butyl acrylate-acrylic acid-4,4,9- trirnethyl-8-oxo-7-oxa-4-aZ0nia-9-decene-1 sulfonate interpolymer, as described herein, (coverage 35 mg./ft. and (2) an unhardened gelatino silver chlorobromide emulsion (coverage 260 mg. silver/ft. 1130 mg. gelatin/ft?) and a hydroquinone tanning developing agent (coverage mg./ft.

After exposure, the element is processed in the usual manner using the following solutions.

SOLUTION A Activator: G. N32C03H2O NaOH 58 KBr 28 dissolved in one liter of water and used at room temperature, activation time thirty seconds to one minute.

SOLUTION B Tanning Inhibitor: G. N21 SO 50 dissolved in one liter of water, used at room temperature, treatment time-thitry seconds.

SOLUTION C Acidifying solution: G Citric acid 50 NaCl 50 dissolved in one liter of water, used at room temperature, treatment timethirty seconds.

The processed element is used to make a resist for a Gravure plate, as described in Yackel U.S. Pat. 3,148,063. The emulsion layer is contacted against the wet metal surface and the polyester support stripped away. The stripping layer is then removed with warm water.

Thus, by the practice of this invention there is obtained novel interpolymers which exhibit an excellent combination of properties which make them particularly useful in photographic silver halide emulsions. The photographic elements containing these interpolymers exhibit improved dimensional stability and salt tolerance. The novel interpolymers can be used as replacements for all or part of the usual binding agents which are generally employed in photographic elements. For example, the novel interpolymers described herein can be used in photographic silver halide emulsion layers, stripping layers, backing layers, anti-abrasion layers and the like.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. An interpolymer which is substantially water insoluble comprising (1) units of acrylic acid, (2) units of monomer represented by the formula:

where R is a hydrogen atom or methyl group and R is an alkyl radical with (3) units of monomer having the formula:

where R is a hydrogen atom or alkyl group, R and R are each divalent saturated aliphatic hydrocarbon radicals and R and R each represent hydrogen atoms or alkyl groups; wherein said interpolymer comprises up to 15 by weight, of said (1), at least about 75%, by weight, of said (2) and up to about 10%, by weight, of said (3).

2. An interpolymer according to claim 1 comprising (1) about 5 to about 15%, by weight, units of acrylic acid, (2) about 75 to about 93%, by weight, units of alkyl acrylate and (3) about 2 to about by weight, units of monomer having the formula:

where R is a hydrogen atom or an alkyl group, R and R are each divalent saturated aliphatic hydrocarbon radicals and R and R each represent hydrogen atoms or alkyl groups.

3. A film forming interpolymer according to claim 1 comprising (1) about 5 to about by weight, units of acrylic acid, (2) about 75 to about 93%, by weight,

10 units of alkyl acrylate and (3) about 2 to about 10%, by weight, units of monomer having the formula:

where R is a hydrogen atoms or an alkyl group, R and R are each divalent saturated aliphatic hydrocarbon radicals and R and R each represent hydrogen atoms or alkyl groups.

4. A film forming interpolymr according to claim 1 comprising (1) about 9%, by weight, units of acrylic acid, (2) about 83%, by weight, units of butyl acrylate and (3) about 8% units of 4,4,9-trimethy1-8oxo-7-oxa-4- azonia-9-decene-1-sulfonate.

5. A film forming interpolymer according to claim 1 comprising (1) about 9%, by weight, units of acrylic acid, (2) about 83%, by weight, units of butyl acrylate and (3) about 8%, by weight, units of 5,5,10-tri1nethy1-9- oxo 8-oxa-5-azonia lO-undecene-l-sulfonate.

References Cited UNITED STATES PATENTS 2,839,401 6/1958 Gray 96-96 3,345,346 10/1967 Reynolds 260-793 JOSEPH L. SCHOFER, Primary Examiner C. A. HENDERSON, JR., Assistant Examiner US. Cl. X.R.

P011050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 54 5 Dated December 7 Inventor) Thomas K. Dykstra and Thomas E. Whiteley It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lines 20-22, the formula should be CH =C -c -0R Column 6, line 29, "equa should be -aque- Column 8, line 31 "thitry" should be ---thirty-.

Signed and sealed this 15th day of June 1971.

(SEAL) Attest:

EDWARD I'LFLETCHER, JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents 

